Hey guys finally swapped out all the pins from a 98 pcm to a 2002 pcm! Everything is working great so much nicer to tune just cant get the fuel gauge to work. Using efilive any help would be greatly appreciated. Thanks in advance.

 

You need to do a fuel segment swap from an 02 express van tune to your new tune. If your not sure how to do the swap then do a search this has been covered 100 times. There is also a table that needs to be inverted otherwise the gauge will work backwards. I forget which one though.

 

Congratulations on doing what very few individuals or even shops do. In order to do the fuel segment swap with a 02 express van you will need to do a unorthadox wire swap. Did you get the former (98) Red 36 to (new setup) Red 38? It is a dark blue wire. You will note that the Red 38 pin is not used in the stock 99+up configuration.

Get fuel segment swap done and enjoy the FREE custom OS's!

Cheers,

Doc

 

would this fix an erratic gauge. i have a 97 cluster in my car, swapped to a ls motor, was running a 99 pcm, had an unfortunate failure and then picked up a 01 pcm and now have an erratic reading sometimes.

 

https://ls1tech.com/forums/pcm-diagn...onversion.html

 

I did the conversion awhile back. This is the only issue I'm having. Red pin 38 on 99-up PCMs shows that it's not used (on diagrams/pinouts). There is no output to the fuel gauge in the dash. It blows my mind it's not listed on any 99-up schematics. This tells me one of two things.
#1 The 99-up PCMs does not control the fuel gauge in the dash. I tried directly connecting the purple wire(from sending unit) to the dark blue wire (to dash gauge). That did nothing but put the level to empty, and stuck it there.
#2 The fuel gauge output from the PCM is not pin 38 on the red connector. I had it hooked up to that and filled in the fuel segment tables with min and max values and the gauge didn't change. So it seems that it couldn't be pin 38. I do know the dark blue to the fuel gauge was on pin 36 on the 98 pcm.

 

yeah im still *** deep in trying to get it to work lol ran into a small problem, spun a rod bearing lol so its on hold until i pull the motor tomorrow but the swap wasnt that hard just time consuming about four hours for me to do it start to finish. i couldnt stand the 98 pcm tuning that thing i think is an effort in stupidity. but i will have to look at that pin when i get it all back together. i loaded the fuel segments from the van then copied with labels from a stock 2002 camaro tune the values in the fuel system and still nothing gauge still reads full but ill get it eventually

 

Right-It's not used on a stock setup. You are not going to be stock anymore by any means. This is the beauty of having the ability to splice the tranny segement w/ the express van. The pcm on the express van is the same/compatible piece of hardware- the tranny segment in the software make the pin "active." So no, you will not find any GM diagram that lists this. That is, except the express van.

Done this many, many times now. It works. Re-check everything wiring wise and software wise.

Doc

 

..I thought you was suppose to swap the fuel segement tables, not trans segements? I also thought you was suppost to just use the calibration values of the express van. Changing the hard code is not as simple a swapping sections with others. Within segments of code are locations to jump to and stuff like that. The segements from one cal might not be in the same location or point to the same location. I also thought that pin control was done through the calibration switchs? Could you post up screen shots of exactly what you are talking about? I'm trying to do this through tunercat. They modified a version to allow access to the fuel level tables/constants. I know they will work with me to get this done. I just dont understand 100% at this point...

thanks,

 

it should be the fuel segment swap, really all your doing it enabling the pwm output for the fuel gauge cluster. That function is not in the software. Both use OS 12212156 so no altering of code shoudl be required.

The calibration tables are broken up into 7 segments plus the OS, these segments should be all calibration data, without the jumps and such. Changing the OS is a lot more complicated.


Ryan

 

Tunercat has a program that will allow editing the calibration via hex editor(sort of). Do you know the location and the value that needs to be set to, in order to enable the pin?

 

Anyone figure this out? I repinned my 98 to a 99 and of course the gauge is inop. I replaced the sending unit with the 99 piece and still no gauge! What gives?

 

the 99+ecu transmits the fuel level signal to the cluster via the serial line, not it's own wire like the 98.

 

you have to do the fuel segment swap, to turn on the PWM output of the 99+ pcm to send the signal to the gauge.

What tuning software are you using?

Ryan

 

I am using hp tuners. Is there any way to do it with HP?